Produção de catalisadores a base de zinco a partir de compostos recuperados de pilhas alcalinas exauridas e aplicação na degradação catalítica de corante têxtil

Abstract

In this work we studied the recovery of zinc and manganese metals for the production of catalysts from depleted alkaline batteries for application in the degradation of the reactive blue dye 5G. With the synthesized catalysts based on zinc (CZn) and manganese (CMn), photocatalytic and catalytic tests were performed, respectively, with 300 mL of dye solution at initial concentration of 100 mg L1, kept under constant stirring along with the catalyst, during the reaction time. For the CZn catalyst, tests were performed to find a working range with good dye degradation, modifying values of catalyst dosage and adsorption time. From the results obtained, it was found that a catalyst dosage of 1 g L1 and adsorption time of 30 minutes provided approximately 80% of dye degradation. The initial pH of the dye solution was 7, since the neutral pH is close to the value found in effluents from textile industries containing the reactive blue dye 5G. For the catalyst CMn a DCCR 22 experimental planning was performed having as independent variables the pH and the dosage of catalyst, and as response variable the percentage of degradation of the reactive blue dye 5G. The optimum point found by the experimental planning was pH 1.7 and catalyst dosage of 1.2 g L1, achieving a degradation of approximately 84%. The XRD, FTIR and SEM characterization analyses were performed in order to obtain information about the structure and morphology of the produced materials, being indicated the formation of zinc and manganese based compounds (ZnO and ZnMn2O4). Finally, the production of both catalysts proved to be technically and environmentally feasible, using the concept of circular economy, creating products and reducing environmental impacts from the disposal of liquid waste (effluents containing textile dyes) and solid waste (alkaline batteries).